This invention relates to a hydraulic coupling device for connection to a multi-line hose constituted by a plurality of hydraulic conduits bunched together. The invention is particularly useful in the hydraulic distribution systems used in underground mine workings, particularly for hydraulically advanceable mine roof support assemblies and other hydraulic appliances.
Systems are known in which numerous hydraulic conduits are bunched together to form multi-line hoses. Multi-line hoses are interconnected by means of pairs of complementary hydraulic coupling devices. One coupling device of each pair houses a plurality of male plug pins which are attached to the conduits of one multi-line hose; and the other coupling device of that pair houses a plurality of female plug pins which are attached to the conduits of a second multi-line hose. The female plug pins mate with the male plug pins when the two coupling devices are attached (usually by the interengagement of complementary screw threads on their casings), thereby connecting the two multi-line hoses. A hydraulic coupling device of this type is described in German Patent Specification No. 1255417.
Known hydraulic coupling devices use specially-constructed plug pins, each of which has to be made to conform with the structure of the particular hydraulic coupling device it is to form part of. This leads not only to high production costs (because many different types of plug pin have to be manufactured), but also to extensive storekeeping costs (because a multiplicity of plug pins--and multi-line hoses prefabricated with such plug pins--have to be stored and indexed).
In underground mine workings, it is common for hydraulic conduits to be laid singly. Such single-line hoses are connected together by mating male and female plug pins. Such a plug pin has a circumferential groove in its exterior peripheral surface, the mating pair of plug pins being held together by means of a hose clip which engages within these grooves. Such plug pins are standardised, each plug pin having standard dimensions and having a groove of standard width, the standard dimensions and width being determined by the pressure-rating of the associated hose line. Consequently, only a few types of plug pin need to be manufactured and stored for single-line hose connections. Such plug pins will be referred to throughout this specification as "standard plug pins".